I built a Progressive Receiver (W7ZOI) last year with si5351 and stayed with the original dual conversion frequency mixing scheme, a first (tuneable) IF of 3.5-4MHz, second IF 9MHz. I used all 3 si5351 clocks, first for VFO, second for heterodyne osc, 3rd for BFO. It was riddled with birdies, unusable. First I built a crystal BFO and buffer, eliminating the need to use the third si5351 clock. Made almost no discernible difference. Finally I ditched the dual conversion scheme and reconfigured it into a single conversion superhet with high side VFO. Problem fixed. Well almost. There are still a few odd birdies, but just a handful, all are well below the usual received signals. I now use this receiver frequently on 160 to 40m and it works well. has some gain distribution issues but that's a different problem.
I suspect the clocks are rich in harmonics and that by placing f-VFO above f-IF they no longer bother me.
My rx has tight receive BPFs. It could be shielded better.
I also started scratch building a uBitx and got it receiving, kind of, not really, lost interest for another build, will come back to it one day.
Regards Paul VK3HN.